I feel the same. I am genuinely baffled that so many people on here leave their door unlocked. Several of my neighbours (rural village) used to do this. Door unlocked at night, whilst children and adults slept, and also unlocked when they went out. They even left the car doors unlocked.
There was an incident where someone staying with a family down the road - a mate of the adult son who he had met recently who had nowhere to go as his parents had kicked him out, (aged late 20s.) One night a woman was sitting in her living room with her 6 y.o. daughter, and this young man just let himself in, and stole her car keys off the little table in the hall, and drove off with her car. (He was picked up on the ring doorbell.) He went on to crash her car. Wrecked it. He was OK. When he was picked up by police, it turned out he had several offences against him for assault against a woman, and petty thefts, and attacking a policeman. That young woman was very lucky he just stole her car.
She has never left the door unlocked since. When she is in, OR out. Everyone around the village made sure they kept their doors locked too after that!!!
Some people on here seem to think it's odd to lock your doors, and seem almost proud that they don't - and claim they don't NEED to. Don't think you don't need to because you live in a 'nice' area. 'Nice' areas are targetted because criminals know there is likely to be some wealth there!
And no, it's NOT a myth about the insurance. They very often will not pay out if you have left doors and windows unlocked/open. The woman in question I spoke about did not get the insurance payout for her car, as she had left her front door unlocked, and the thief obtained the car keys because of this. She had to find money for another car, and could only afford one that was 15-16 years old. (Cost her £1200.) Her other one was 6 years old and she had paid £5500 for it just a year earlier. So she made a huge loss there, because the insurance would not pay up.